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J. WHlTEHlLL PRESSURE RESPONSIVE INDICATING APPARATUS MarchV 3l, 1964 Filed June 13, 1960 5 Sheets-Sheet 1 March 3l, 1964 J. wHlTr-:HILL 3,126,739

PRESSURE RESPONSIVE INDICATING APPARATUS Filed June 13, 1960 5 Sheets-Sheet 2 37 FIGUREZ 38 F -V 42 45 4e 43 4?) 4,8 oETcToR osclLmoR l unieron MOTOR CONTROL 50 Arran/frs March 31, 1964 Filed June 13, 1960 J. WHlTEHlLL PRESSURE RESPONSIVE INDICATING APPARATUS 5 Sheets-Shea?I 3 FIGURE 6 3%@ EMM fm2-p ATTORNEYS 5 Sheets-Sheet 4 Filed June 13, 1960 FIGURE 9 FIGURE 8 w fvn R w 8 ////4L2 m Mm all M ,R i MM Wm l r A w. m@ v m Em\\\\\-.\ IW@ E 3 w JW m /Z/@w/Ay/ l w .M m

6I 2 wwmsw mwmmmy llldl 2 ld B I 2 w y E H u w E R w E|\\/ U F. l G J nl. RJ 14, Eo s Mmmm@ mmm m March 31, 1964 J. WHITEHILL.

PRESSURE RESPONSIVE INDICATING APPARATUS 5 Sheets-Sheet 5 Filed June 13, 1960 FIGURE I3 FIGURE l2 6 O 2 Mmm M 13%@ MjmnLm-W/z ATTORNEY 3 United States Patent O 3,126,739 PRESSURE RESPONSIVE INDICATING APPARATUS Joseph Whitehill, Easton, Md., Filed June 13, 1960, Ser. No. 35,751 Claims. (Cl. 73-205) This invention relates to apparatus for indicating pressure changes and more particularly to a pressure responsive apparatus for indicating changes in the relative velocity between said apparatus and a iiuid medium.

In many situations where there is relative movement between a device and a iiuid medium, it is desirable to obtain an indication of the fact of change in the velocity of such relative movement (i.e., acceleration or deceleration. Frequently the indication of change should be independent of the magnitude of the relative velocity. While some devices capable of indicating the fact of velocity change have been available heretofore, they have generally been attended by certain disadvantages such as high initial and maintenance cost, undue complexity, poor readability, insutlicient sensitivity, lack of ruggedness and the like.

To overcome the disadvantages of prior art devices, it is an object of this invention to provide a pressure responsive apparatus for indicating change in the relative velocity between the apparatus and a fluid medium which is very dependable and yet is easy to read, simple, rugged, and inexpensive in both initial and maintenance cost.

A further object of the invention is to provide such an apparatus which is insensitive to the magnitude of the relative velocity between the apparatus and a fluid medium.

A further object of the invention is to provide such an apparatus which is insensitive to changes in the static pressure of such medium.

Stili another object of the invention is to provide such an apparatus which is easily alterable as to sensitivity.

It is yet another object of the invention to provide such an apparatus including an electrical indicator of change in relative velocity between the apparatus and a fluid medium.

It is still another object of the invention to provide such an apparatus including means automatically to govern the amount of motivating power causing a vehicle to travel in a iuid medium so as to compensate for changes in the velocity of the vehicle.

it is a further object of the invention to provide an improved uid pressure balancing device having particular utility with such an apparatus.

It is a still further object of the invention to provide an improved device for indicating direction of fluid flow iinding particular utility with such an apparatus.

it is another object of the invention to provide an improved and highly sensitive apparatus for indicating tiuid pressure changes.

In general, the apparatus of the invention embraces an indicating device in combination with appropriate fluid control means. The indicating device includes one or more iiow responsive elements mounted in one or more conduits through which fluid may flow to actuate the indicator. The control means is responsive to the relative velocity between the apparatus and a tluid medium to cause tluid ow in the conduit in which the indicator element is mounted when the relative velocity changes and to prevent such iiuid flow when the relative velocity is constant. Preferably, while the indicator element moves in response to change in the relative velocity, its position in the conduit is independent of the magnitude of such velocity and it returns to its normal position when the relative velocity becomes constant.

3,l2h,739 Patented Mar. 31, 1964 The invention finds particular utility in indicating change in the velocity of a vehicle traveling through a fluid medium, for example, a boat traveling through the water or an aircraft or missile traveling through the air. it will be understood, however, that the invention also may be employed at a iixed location to measure change in the velocity of a uid moving past such location. For example, the apparatus may be connected to a pipe line to indicate changes in velocity of a liquid or gas traveling through the pipe line.

Certain specific embodiments of the invention will now be described in detail with reference to the acompanying drawings in which:

FIGURE 1 is a sectional View of the apparatus of the invention as employed in a boat to indicate change of velocity of the boat as it passes through the water;

FIGURE 2 is a sectional view of an alternative form of indicator according to the invention with a schematic showing of the electrical circuitry thereof;

FIGURE 3 is a horizontal sectional View taken along the line 3--3 of FIGURE 1;

FIGURE 4 is a vertical sectional view taken along the line 4-4 or FIGURE 1;

FIGURE 5 is an'isometric view of the end of one of the pipes leading into or out of the indicator tube;

FiGURE 6 is a bottom plan View of the detector assembly;

FIGURE 7 is a view partly in section of a modified and preferred embodiment oi the apparatus of the invention;

FIGURE 8 is a sectional view of a preferred form of balancing chamber;

FIGURE 9 is a sectional View of another alternative and preferred form of indicator according to the in- Vention;

FIGURE 10 is a sectional view taken along the line It-lil of FIGURE 9;

FIGURE 11 is a sectional view taken along the line .1i-41 of FIGURE 9;

FIGURE 12 is a sectional View taken along the line 12-12 of FIGURE 9; and

FGURE 13 is a view of the inside face of the cover plates for the indicator of FIGURE 9.

With reference to the embodiment of the invention shown in FIGURE 1, there is provided as a part of the apparatus a uid pressure balancing chamber 1 having a pair of housing parts 2 and 3. The latter are generally cup-shaped and are provided with annular flanges 4 and 5 at their open ends. The flanges 4 and 5 are joined by any suitable fluid tight connecting means, not shown, such as by bolting or cementing, with the periphery of a diaphragm 6 sandwiched therebetween. The diaphragm 6 provides a fluid pressure responsive wall which is mounted for resilient yielding and separates the balancing chamber 1 into a pair of smaller chambers 7 and 8. The diaphragm 6 may be made of metal, rubber, synthetic material, or any appropriately elastic substance. Formed in each face of the diaphragm are a plurality of concentric annular depressions 9 which tend to flatten when the diaphragm 6 is exposed to unbalanced uid pressure on its opposing faces. Thus the diaphragm yields resiliently and is displaced to a limited extent under the force of such unbalanced pressure. When the unbalance in the uid pressure is constant, the diaphragm will deflect a xed amount, its resilience compensating for the tiuid pressure unbalance. When the unbalance increases to a given extent, the diaphragm will yield to a new stationary position. Correspondingly when there is a decrease in the pressure on the concave side of the displaced diaphragm, its resilience will cause it to assume a fixed position of less displacement. The resilient resistance to deflection of the diaphragm should be suicient to prevent its strikta ing the outer wall of the chamber 1 over the normal range of operation.

It will be understood that the particular diaphragm and mounting disclosed in the drawing are exemplary only. Various equivalent structures may be employed. For example, a smooth diaphragm without the depressions 9 may be employed especially where the diaphragm comprises a highly resilient substance such as rubber. If desired, springs may be used to resist yielding of the diaphragm. Moreover a convolute bellows assembly of elastic material or a piston opposed by springs on each side or otherwise mounted for resilient yielding might be substituted for the diaphragm.

The chamber parts 2 and 3 are provided with closure plugs 11 and 12 which are threadably received in corresponding internally threaded bosses 13 and 14. Openings to the pressure tight chambers 7 and S are provided by flanged tubes 15 and 16 which are xed to the chamber parts 2 and 3, respectively, by welding, cementing or otherwise to prevent leakage around the tubes.

The tubes 15 and 16 are connected by a pair of conduits 18 and 19 to a Pitot tube detector assembly 17 which is mounted on the bottom 2'3 of a boat below the water line. The detector assembly includes a housing 20 which contains a Pitot tube 21 and a static tube 22. The housing 17 is very slim and streamlined to decrease its resistance to ow therepast. Moreover the front of the housing is steeply inclined rearwardly to minimize collection on the housing of weeds or other foreign material which might block the openings of the tubes 21 and 22. The conduit 18 is connected to the Pitot or dynamic tube 21 which has an opening exposed to the water and facing toward the front of the boat to sense dynamic tluid pressure in the usual manner when the boat is moving. The conduit 19 is connected to the static tube 22 which has a pair of openings also exposed to the water .but directed laterally of the boat so as to be constantly responsive only to static pressures even when the boat is moving. Thus the Pitot and static openings are connected by a long conduit formed by the fluid conducting components described, across which conduit the diaphragm 6 extends to prevent duid ilow completely through such conduit but to permit limited ilow in all portions of the conduit due to the yielding of the diaphragm.

The Pitot and static tube openings are fixed against vertical movement relative to one another so that the operation of the device is independent of changes in the static pressure resulting, for example, by increase or decrease in the depth of the water above the openings. Preferably, the Pitot and static openings are approximately at the same level so as to sense substantially the same static pressure. Since the theory of operation of a Pitot tube assembly is well known, it will not be discussed in further detail.

The conduit 18 includes an indicator tube 24 of glass or other transparent material, such as a transparent plastic, which contains a shuttle ball 2'5, which serves as a movable indicator element. The shuttle ball 25 in the embodiment shown in FIGURE l has a lower density than water and may be either solid or hollow. The indicator tube 24 serves as a fluid conduit and is generally U-shaped with the crown 26 of the U disposed at a higher elevation than the legs 27 and 2S of the U. Thus the crown 26 forms a bend at the upper vertical extremity of the tube 24. Thus, when the indicator tube 24 is lled with water and the water is at rest, the shuttle ball 24 will oat upwardly and settle at the crown of the U-shaped tube as shown in solid lines at FIGURE 1. When there is a movement of the water in the tube 24, the shuttle ball 25 is displaced by such movement in the direction that the water is traveling as shown in dotted lines in FIGURE l. Upon cessation of the water movement, the shuttle ball 25 once again will float to the crown 26 of the U-shaped indicator tube.

As shown in FIGURE 1, the inside diameter of the indicator tube increases from the crown portion ontwardly toward the ends of the leg portions so that the device is very sensitive when the shuttle ball is at the center or zero position and yet will permit a large tiow of water past the ball when it is near the end of one of the legs of the tube. This outward flare may begin at positions spaced from the center of the crown portion 26. Alternatively, the inside diameter of the tube 24 may increase progressively all the way from the center of the crown portion 26 to the ends of the legs 27 and 23.

The ends of the indicator tube 24 are sealed by a pair of water tight plugs 31. Mounted in each of the plugs 31 by a duid-tight connection is a hollow pipe 32. The openings at the inner ends 33 of the pipes 32 are smaller in diameter than the shuttle ball 25. Thus the pipe ends serve as stops to limit the travel of the shuttle ball. Further, the pipe ends 33 are convex so that their openings have a configuration which does not correspond with the configuration of the shuttle ball 25 to permit the passage of tluid into and out of the pipe ends even when the shuttle ball is resting thereagainst.

The outer end of one of the pipes 32 is connected to the outer end of the tube 15 on the chamber part 2 by means of a flexible tubing 37. The outer end of the other pipe 32' is connected to the upper end of the Pitot tube 21 by means of liexible tubing 38. The outer end of the tube 16 in the-chamber part 3 is connected to the static tube 22 by means of flexible tubing 39. The ilexible tubing should be substantially non-elastic to prevent its dilation under pressure. All of the various connections in the system are fluid tight. If desired, the entire system including conduits 18 and 19 and the balance chamber 1 may be transparent or translucent to facilitate detection and removal of entrained air bubbles.

The apparatus is mounted on a boat with the detector assembly 17 in the water and the indicator tube 24 visible to the crew of the boat. Preferably the long axis of the tube 24 is aligned with the direction of movement with the rear of the tube 24 connected to the Pitot tube 21. Thus forward acceleration is indicated by forward movement of the shuttle ball 25 as more fully described hereinafter.

In operation, the pressure of the water causes an inow into the static tube 22 and Pitot tube 21 to ll the conduits 18 and 19 and the chambers 7 and 3 if air is released from the system by removing the plugs 11 and 12 until the chambers are full and then replacing them. As long as the boat is at rest in the water, the static pressure and the Pitot or dynamic pressure are equal so that the pressure in the chambers 7 and S on opposite sides of the diaphragm 6 are equal. Thus, there is no deilection of the diaphragm. When the boat moves forward at a constant velocity, the Pitot tube 21 senses the dynamic pressure of the water while the static tube 22 continues to sense the static pressure. There is thus induced in the chamber 7 the dynamic pressure which is equal to the static pressure of the water increased by an amount proportional to the square of the relative velocity between the boat and the water. Since the pressure in the chamber 8 remains equal to the static pressure of the water, the diaphragm 6 will be deflected to the right as shown in FIGURE 1 to a given position. As long as the relative velocity remains constant, the diaphragm d, while detlected, will remain stationary so that there is no movement of the water in the tubes 18 and 19. When there is an increase in velocity, however, the pressure in the chamber 7 will be increased to cause the diaphragm 6 to move to the right (as shown in FIGURE l) and to effect a temporary ow of water through the conduits 18 and 19. The flow through the tube 24 displaces the shuttle ball 25 to the left as shown in FIGURE l. The movement of the diaphragm d and the temporary flow through the tube 2% continues as long as the velocity continues to change. When the velocity again becomes constant at the increased amount, the pressure differential on opposite sides of the diaphragm 6 will become constant and the resiiient resistance of the diaphragm to displacement will bring it to a stop thereby preventing further flow of fluid in the conduit system. Upon cessation of the temporary how in the tube 24', the shuttle ball 2S will float to the center of the crown 26 of the U-shaped indicator tube. it follows that when there is a decrease in velocity f the boat through the water, tee diaphragm 6 will move in the opposite direction and there will be a temporary tlow in the tube 24 in the opposite direction. The shuttle ball 25 will then be displaced to the right of the crown 26 (as shown in FlGURE 1) and upon cessation of the temporary flow due to stabilization of the velocity at a lower constant rate, the shuttle ball 25 will again return to the crown or zero position of the indicator tube.

The sensitivity of the indicator may be varied by changing the diameter of the ball 25 with respect to the inside diameter of the tube 24. When the ball is nearly large enough to till the tube, it will be noticeably deiiected by a very slow rate of change in velocity of the boat and will return to the zero position very slowly when the velocity again stabilizes. As an example of the great sensitivity that can be achieved, it has been found that an increase in speed of .0l knot can be detected when the boat is traveling at about 1.5 knots. When the ball 25 is considerably smaller than the inside diameter of the tube 24, there will be little deflection at a slow rate of change of velocity and the ball will return to the zero position much more quickly. In a boat which has limited acceleration, it is preferable to employ a shuttle ball which is large relative to the indicator tube. Correspondingly, in a boat which is capable of very rapid acceleration, a ball considerably smaller than the indicator tube would be desirable. Thus several balls of varying diameters may be provided for individual use depending upon the desired sensitivity.

Disclosed in FIGURE 2 is a modified form of indicator tube 4].. The tube 41 is mounted in the system in the same manner as the tube 2d and is identical thereto except that the tube 41 is inverted with respect to the tube 24, i.e., the tube 41 is generally U-shaped with its middle portion disposed below its leg portions to form a bend at its lower vertical extremity. The tube il contains a shuttle ball 42 which is more dense than water. The ball 42 normally rests at the central or zero position of the generally U-shaped tube 41 and is displaced therefrom by temporary movement of uid in the tube 41 in the same manner as previously described. When there is a cessation of flow of fluid through the tube 41, the shuttle ball 42 returns by gravity to the central or zero position in the tube 4l. The tube il may be transparent so that the movement of the ball 42 may be observed. In the embodiment shown in FIGURE 2, however, it is not essential that the tube 41 be transparent because electrical means are provided to indicate displacement of the shuttle ball 42 corresponding to a change in veiocity of the boat through the water.

The ball 42 is made of ferromagnetic material. An electrical system 43 is provided to detect displacement of the ball 4Z. This system includes an oscillator i4 which generates continuous alternating current at a particular frequency. The current generated by the oscillator is divided and fed equally to two identical LC bandstop filters 45 and 46. The resonant inductance of each of these filters is provided by ya coil of wire surrounding one leg of the U-shaped indicator tube 41. These coils are shown at 47 and 4S. The filters also include capacitors and 56 connected across the coils 47 and 41.3 respectively. The filters i5 and 46 are connected to detectors 47 and 4S which in turn are connected to relays 5l and 52 which operate switches 53 and 54.

When the ferromagnetic shuttle ball 42 is at rest in the zero position in the indicator tube, the resonant frequency of the tank circuit in each of the LC filters is the same' as the fundamental frequency of the oscillator. Thus, the energy of the oscillator is blocked by the high impedance of the filter and no current or substantially none reaches the detectors 47 and 48. It will be understood that iilter circuits may be employed which shunt the current out of the oscillator to ground instead of stopping it by high filter impedance.

When the ball is driven toward one or the other of the coils 47 or d8, its passage through such coil changes that coils inductance radically which in turn changes the resonant frequency of that particular LC filter. Energy then may pass the filter and enter the detector. The function of the detectors is to rectify the yalternating current that passes the lters into pulsating direct current for operating of the relays. The associated relay is actuated to operate its switch which is included in a related circuit (only one of which is shown) so as to actuate a signal such `as a bell 50, and a conventional speed control device 69 connected to the boat motor. The control device 60 could comprise, for example, a pair of stepping solenoids connected to the motor throttle. When the boat accelerates, one of the control devices 60 is operated to decrease the speed of the motor and correspondingly when the boat decelerates the other control device is operated to increase the speed.

If desired, either the signal 59 or the control device 60 may be eliminated from the switch circuits and the other retained.

It will be understood that the specific electrical circuitry shown in FIGURE 2 is exemplary only. Many different circuits could be employed to accomplish the same result.

The indicator tube 24 or 41 may be mounted in the conduit 18 as shown or, alternatively, may be mounted in the conduit 19, since congruent and reciprocal temporary liowing or water will occur in both conduits at the same time. Moreover, two indicator tubes may be used simultaneously, one in each of the conduits 18 and 19. Still further, a multiplicity of indicator tubes could be employed in series in either or both of the conduits 1S and 19 if multiple observation points are desired.

The particular forms of indicator assemblies shown in FIGURES l and 2 are illustrative only and alternative types of indicators may be employed within the broad framework of the invention. For example, the shuttle ball might be a gas inflated soft plastic bubble that actually touches the bore of the indicator tube all around.

Further, the indicator tube can be perfectly straight and positive means other than a bent tube may be used to return the shuttle element to its Zero position. For example, the shuttle ball 25 or 42 could be returned to the center position by a pair of opposing compression springs rather than by floating or gravity. Moreover, the shuttle ball could be replaced by a flat vane or gate extending across the tube bore and pivotally connected at its upper end to the zero position for deflection by fluid flow in either direction and return by gravity to a vertical position upon cessation of how. Alternatively, a flexible indicator such as a fuzz ball or a piece of fabric could be attached at its upper end to the zero position in the tube to be swung into a horizontal or near horizontal position by the temporary ow and to return to a vertical or otherwise collapsed position upon cessation of the flow. The ferromagnetic shuttle ball 42 could be returned to its zero position by magnetic means such as a U-magnet disposed with its poles on opposite sides of the indicator tube at the zero position.

Moreover, indicators other than a viewable shuttle element may be employed. For example, a movable element might be employed in the indicator tube to actuate a mechanical indicator located outside of the indicator tube.

Shown in FIGURES 7 through 13 is a preferred form of the apparatus of the invnetion which is identical to the device of FIGURE l except that the former embodies 3,1 7 alternative and preferred forms of indicator and balancing chamber. The general manner of operation of the devices of FIGURES 1 and 7 is the same.

The balancing chamber 101 is shown in FIGURE 7 and in section in FIGURE 8. 1t includes a housing having two parts 102 and 103 which are generally cup-shaped and are provided with annular flanges 1114 and 105 at their open ends. Such ilanges are joined by a fluid tight connection which includes the bolts 196 or any other suitable fastening means with the periphery of a diaphragm 1117 sandwiched between the anges. T le diaphragm 1tl7 provides a fluid pressure responsive wall which is mounted for resilient yielding and separates the balancing chamber 101 into a pair of smaller chambers 168 and 1439. The diaphragm 167 is formed of rubber or any other suitable material having the general resilient characteristics of rubber. The diaphragm 197 is highly resilient and when there is even a slight increase in the pressure in the chamber 10S relative to the pressure in the chamber 109 the diaphragm 107 will deliect toward the chamber 109 as shown in dotted lines in FIGURE 8.

The wall of the housing part 1193 tapers inwardly away from the diaphragm 107 so that its cross-sectional area progressively decreases away from the diaphragm. To achieve such a taper the housing part 1&3 preferably is frusto-conical in configuration. Thus when the diaphragm flexes due to relatively high pressure in the chamber 1118 the peripheral portion of the diaphragm is flattened against the truste-conical wall of the chamber 1129 leaving as the effective area of the diaphragm only that portion in the center of the diaphragm which is free of the chamber walls and extends thereacross. Consequently when the pressure in the chamber 1193 relative to the chamber 1119 progressively increases, the diaphragm ilexes into increasing engagement with the frustoconical inner wall of the chamber 1119 to decrease progressively the effective area of the diaphragm extending across the housing.

The tapered configuration of the chamber 1119 is characterized by an important advantage. When the diaphragm 107 is subjected to unbalanced pressure it tends to assume the form of a sphere. lf the resistance to the unbalanced pressure is assumed solely by the highly resilient diaphragm, it would quickly balloon to a very large size and completely till the housing. lf in compensation, the diaphragm were made extremely resistant to deiiection, its sensitivity would be correspondingly diminished. With the present invention, the peripheral portions of the diaphragm lie llat against the ifrusto-conical housing Wall and the unbalanced pressure is resisted in large measure by the housing wall. Only the free central portion of the diaphragm is subjected to flexure. Accordingly, an extremely resilient and sensitive diaphragm may be subjeoted to a much higher pressure unbalance without an undue increase in the size of the chamber 1119.

The housing parts 1612 and 103 are provided with flanged tubes 111 and 112 which extend through and are affixed by fluid tight connections to the housing parts 1112 and 1113 respectively, to provide tluid connections between the conduit 37 and' the chamber .168 and the conduit 39 and the chamber 109;

The operation of the balancing chamber 1111 is the same as that of the balancing chamber 1. When the unbalance in the ilu-id pressure on opposite sides of the diaphragm is constant the diaphragm will deect a fixed amount, its resilience compensating for the huid pressure unbalance. When the unbalance increases to a given extent, the diaphragm will yield to a new stationary position. Correspondingly when there lis a decrease in the pressure on the concave side of the displaced diaphragm, its resilience will cause it to assume a iixed position of less displacement. The resilient resistance to deilection of the diaphragm and the taper of the housing part 1113 should be selected to preclude the diaphragms striking the extreme aereo end of the housing part 1113 over the normal range of operation.

The balancing chamber 1111 is connected by the conduits 113 and 119 to the Pitot tube detector assembly 17. The conduit 118 includes passageways through a ilow directional indicator assembly 121. lf desired the indicator assembly may be connected to the conduit 119 instead of the conduit 11S. rhe indicator assembly includes a body portion 122 provided with a pair of external connections 123 and 124 to provide iiuid communication between the indicator and the conduits 37 and Sti respectively. Also in iiuid communication with 4the connections 123 and 124 are a pair of passages 125 and 125 respectively, extending in side by side relationship longitudinally from top to bottom of the body portion 122. The tops of the passages 125 and 125 are each closed by a cap 127 which is sealed relative to the passageway and is bored to receive a tapered plug 12S. The plug 123 is received in frictional gripping relationship Within the cap 127 and may easily be removed to permit bleeding of the indicator assembly. The body portion 122 .is also provided with lateral passages 131 and 132 extending yfrom the bottom and top respectively of the longitudinal passageway 125 and passing through the side wall 13d' of the body portion. Similarly a pair of lateral passages 133 and 1341 extend from the bottom and top respectively of the longitudinal passageway 126 through the side wall 13@ of the body portion 122.

Aliixed in sealed relationship as by adhesive bonding to the side wall 1319, is an inner cover plate which overlies the passages 131, 132, 133 and 13d. An outer cover plate 13o is adhesively bonded or otherwise aliixed in sealed relationship to the inner cover plate 135. The inner cover plate 135 is provided with a slot 137 which provides a cross passage connecting in huid communication the lateral passageway 131 at the bottom of the longitudinal passageway 125 with the lateral passageway 134 at the top of the longitudinal passageway 126. The inner cover plate 13S is also provided with a pair of lateral passages 13S and 139 which extend completely through the cover plate 135 and form extensions of the lateral passageway 133 at the bottom of longitudinal passageway 126 and the `lateral passageway 132 at the top of the longitudinal passageway 125. The outer cover plate 136 Iis provided with a slot 141 which forms a cross passage connecting the lateral passages 138 and 139 in the inner cover plate 135.

The system of passageways within the indicator 121 forms a uid conduit arranged in a closed loop. The connections 123 and 124;- communicate with such conduit at diierent locations on the loop. Beginning at the inner end of the connection 123 the closed loop comprises in turn the passageways 125', 132, 139, 111-1, 138, 133, 126, 13d, 137, and 151. Different branches 14u' and 150 of the loop provide alternate flow paths between the connections 123 and 124. The branch 141th moving from the connection 123 to the connection 12d includes the passageways 12S, 132, 139, 141, 138, and 133. rlhe other branch 151i moving `from the connection 12d to the connection 123 includes the passageways 126, 13d, 137, and 131.

Positioned within Ithe passageways 125 and 126 between the lateral passages at the top and bottom thereof are Vvalve seats 1452 and 143 respectively (FiGURE l2), facing away from the connections 123 and 12d. 'Co-operable with the valve seats 1412 and 143 are check valve indicator elements 1st-fi and 145, respectively. `Each of the valves is unseated and moved upwardly when upward fluid low occurs in its passageway. Similarly each of the valves moves downwardly when tluid tends to flow downwardly in its passageway and is seated to prevent such downward ow. To insure substantial movement ot the valves the lower portions 146 and 1F17 of the passageways 125 and 126` are straight or cylindrical with diameters only slightly greater than the diameter of the valves so that only a slight clearance Ifor the valve is provided. The upper portions 148 and 149 of the passageways 125 and 1246 are tapered upwardly to provide a greater clearance for the valves. Consequently, when upward flow occurs through one of the passages 125 or 12d the valve element therein is moved upwardly through the passageway portion 146 or 147. During this initial movement of the valve, very little tiuid escapes around its edges. The valve is therefore moved rapidly upwardly through the straight passageway portion into the tapered passageway portion to permit a greater amount of i'luid to escape around the edges of the valve. Upward movement of the valve elements is limited by the tapered plugs 128, the bottom ends of which serve as stops to prevent the valve elements from seating in the ends of passageways 132 and 134.

The body portion 122 and the cover plates 135 and 136 of the indicator preferably are molded of a transparent synthetic resinous material. The valve elements preferably are of a color which sharply contrasts with the transparent material. 'l'hus the movement of the valves may be clearly observed by an operator. if desired the entire indicator body need not be transparent but instead there may be only a sufficient transparent portion thereof in the vicinity of the valve elements to permit visual observation ot the movement of the valve elements.

As a further alternative, additional indicator means responsive to the movement of the valve elements may be employed outside of the pasasgeways 125 and 126. In this event the indicator body portion need not be transparent. lFor example, the fvalve elements may be of magnetic material and appropriate electrical means may be employed to indicate movement of the valve elements.

In the operation of the indicator assembly 121, fluid tlow into the connection 123 and out of the connection 124 occurs through the branch 14d thereby lifting the valve 144. The fluid cannot iiow through the branch 15d because it tends to move ydownwardly through the passageway 126' and therefore seats the valve 145. Conversely fluid flow into the connection 124 and out of the connection 123 occurs solely through branch .15@ lifting the valve element 1145 and seating valve element 144 to prevent flow through the branch 140. Preferably no flow is permitted past the valve which is seated, but the invention is operable if some leakage around the seated valve is permitted. 'In this event the greater portion of the flow in either direction would occur through `one branch of the loop with a small portion of the ow occurring through the other branch. rll`he valve elements would still effectively open and close to `function as indicators.

With the components assembled as shown in FIGURE 7, an increase 'm the speed of the boat through the water would cause a temporary tlow from the connection 124 to the connection 123` thereby raising valve element 145 and seating valve element 144. Upon a decrease in the boat speed, flow occurs in the opposite direction -rom the connection 123 to the connection 124 to raise valve element 144 and seat valve element 145. In either case, when the speed again becomes constant, the raised Valve element drops by gravity to its original position.

The conduits 38 and 39 may be connected to various pressure sources other than a Pitot assembly and the apparatus functions as a highly sensitive pressure-change indicator.

While the invention has been described with respect to specilic embodiments, it will be understood that other modiiications may be made by persons `skilled in the art without departing from the scope of the invention as embraced by the appended claims.

This application is a continuation-impart of my copending application Serial Number 861,144, tiled December 21, 1959, `entitled Apparatus for indicating Change in Velocity, now abandoned.

I claim:

l. An apparatus for indicating change in the relative velocity between said apparatus and a uid medium which comprises conduit means, resiliently yieldable wall means extending across said conduit means to provide a iuid seal, said conduit means being connectable on one side of said Wall means to a source of tluid under a rst pressure, means responsive to said relative velocity and connected to said conduit means on the other side of said wall means to expose said other side to a second iluid pressure varying from said iirst pressure in proportion to said relative velocity thereby causing said wall means to resiliently yield and uid to ilow in said conduit when said relative velocity changes and said wall means to come to rest and the uid tlow in said conduit to cease when said relative velocity becomes constant, indicator means including a moveable element positioned in said conduit means, and responsive to Huid iiow to indicate a change in said relative velocity, and means to maintain said element at a predetermined location along said conduit means in the absence of iluid ilow to indicate constant relative velocity regardless of the position of said wall means.

2. An apparatus as recited in claim 1 wherein said relative velocity responsive means comprises Pitot detector means having a dynamic opening facing into said fluid medium to provide said second iluid pressure, said detector means having a static opening into said fluid medium and connected to the conduit means on said one side of said wall means to provide said flrst uid pressure.

3. An apparatus as recited in claim l wherein the cross sectional area of said conduit means is substantially less at the location of said element than at the location of said wall means.

4. An apparatus as recited in claim 3 wherein said Wall means comprises a diaphragm and the cross sectional area of said conduit means progressively decreases away from said one side of said diaphragm so that yielding of said diaphragm toward said one side causes said diaphragm to increasingly engage said conduit means to progressively decrease the effective area of the diaphragm extending across said conduit means.

5. An apparatus as recited in claim l wherein said element is moveable longitudinally in said conduit away from said single location in response to duid iiow in the conduit.

6. An apparatus as recited in claim 5 wherein the density of said element relative to the density of the fluid in which it moves and the configuration of said conduit means at said predetermined location are such as to cause said element to move to said predetermined location when the uid is at rest in said conduit means.

7. An apparatus as recited in claim 6 wherein said conduit means has a transparent portion adjacent said predetermined location and said element is visible through said transparent portion to provide said indications.

8. An apparatus as recited in claim 5 wherein said means to maintain said element at a single predetermined location comprises a portion of said conduit means having a bendI at a vertical extremity at said single location, the density of said element relative to the density of the fluid in which it moves being such as to cause said element to move to said vertical extremity when the tluid is at rest in said conduit means.

9. An apparatus as recited in claim l wherein said element contains ferromagnetic material and said indicator means includes electrical means responsive to the movement of said element.

10. An apparatus as recited in claim 9 for mounting on a vehicle driven by power means through a fluid medium wherein said electrical means comprises means to control said power means to govern the speed of the vehicle.

l1. An apparatus as recited in claim 7 wherein the lll inside cross sectional area of said conduit means increases progressively outwardly from said vertical extremity.

12. An apparatus as recited in claim 8 wherein stop means is provided in said conduit means spaced from said vertical extremity to limit the movement of said element.

13. An apparatus as recited in claim 2 wherein said detector means is encased in a thin elongated housing extending in the direction of fluid ilow and having a rearwardly inclined edge facing into the flowing iluid.

14. An apparatus as recited in claim 12 wherein said stop means denes a pair of reduced openings in said conduit means on opposite sides of said vertical extremity, the configuration of said openings being different from the configuration of said shuttle element to permit passage of fluid through said openings when said shuttle element is positioned thereagainst.

15. An apparatus for indicating direction of uid ow which comprises fluid conduit means forming a closed loop, said conduit means having a pair of fluid connections at diierent locations on said loop with diiierent branches of said loop providing separate how paths between said connections, indicator means responsive to direction of lluid flow through said conduit means between said connections and including valve means mounted in said loop to direct at least the greater portion of said fluid flow in one direction through one of said branches and in the opposite direction through the other of said branches.

15. An apparatus for indicating direction of fluid ow which comprises iiuid conduit means forming a closed loop, said conduit means having a pair of iiuid connections at different locations on said loop with different branches of said loop providing separate ilow paths between said connections, indicator means responsive to direction of iiuid dow through said conduit means between said connections and including a pair of check valve means mounted in diterent ones of said branches and oriented to direct at least the greater portion of said fluid flow in one direction through one of said branches and in the opposite direction through the other of said branches, the operation of said check valves providing an indication of the direction of said fluid liow.

17. An apparatus for indicating direction of uid iiow which comprises huid conduit means forming a closed loop, said conduit means having a pair of iluid connections at different locations on said loop with different branches of said loop providing separate iiow paths between said connections, indicator means responsive to direction of fluid flow through said conduit means between said connections and including a pair of check valve means mounted in different ones of said branches and oriented to direct at least the greater portion of said fluid flow in one direction through one of said branches and in the opposite direction through the other of said branches, said conduit means being transparent to expose the operation of said check valve means t-o provide an indication of the direction of said iluid flow.

18. An apparatus for indicating direction of uid ow which comprises liuid conduit means forming a closed loop, said conduit means having a pair of iiuid connections at different locations on said loop with dii'erent branches of said loop providing separate iow paths between said connections, indicator means responsive to direction of fluid flow through said conduit means between said connections and including valve seats and check valves co-operable therewith mounted in each of said branches and oriented to direct at least the greater portion of said vlluid ilow in one directon through one of said branches and in the opposite direction through the other of said branches, said conduit means being transparent to expose the operation of said check valves, said conduit means providing a relatively small clearance for each or" said check valves over an initial portion of a path of movement thereof away from its valve seat and a relatively large clearance for a subsequent portion of said path of movement to effect substantial movement of said check valves and provide a visual indication of the direction of said iiuid iiow.

19. An apparatus as recited in claim 18 wherein the portions of said conduit means in which said check valves move are mounted in side-by-side relationship.

20. An apparatus as recited in claim 19 wherein said loop includes cross passages interconnecting opposite ends of said portions of said conduit means so that opening movement of each of said check valves will be in the same direction.

21. An apparatus for indicating change in the relative velocity between said apparatus and a duid medium which comprises iiuid conduit means forming a closed loop, said conduit means having a pair of fluid connections at different locations on said loop with different branches of said loop providing separate flow paths between said connections, indicator means responsive to direction of fluid flow through said conduit means between said connections and including valve means mounted in said loop to direct at least the greater portion of said iiuid How in one direction through one of said branches and in the opposite direction through the other of said branches, and iiuid control means responsive to said relative velocity and connected to said duid connections to cause fluid iiow in said branches between said connections in opposite directions to activate said indicator means when said relative velocity increases and decreases respectively and to prevent iiuid iiow in said branches when said relative velocity is constant.

22. An apparatus for indicating change in the relative velocity between said apparatus and a fluid medium which comprises iluid conduit means forming a closed loop, said conduit means having a pair of iiuid connections at different locations on said loop with diferent branches of said loop providing separate flow paths between said connections, indicator means responsive to direction of iluid flow through said conduit means between said connections and including valve means mounted in said loop to direct at least the greater portion of said fluid flow in one direction through one of said branches and in the opposte direction through the other of said branches, detector means responsive to said relative velocity and adapted to be positioned in said uid medium, said detector means being connected to said fluid connections to cause uid flow in said branches between said connections in opposite directions to activate said indicator means when said relative velocity increases and decreases respectively, and iiuid pressure responsive balancing means connected between one of said connections and said detector means to stop the iiuid iiow in said conduit when said relative velocity becomes constant.

23. An apparatus for indicating change in the relative velocity between said apparatus and a iiuid medium which comprises uid conduit means forming a closed loop, said conduit means having a pair of fluid connections at diiferent locations on said loop with different branches of said loop providing separate ow paths between said connections, indicator means responsive to direction of fluid ow through said conduit means between said connections and including a pair of check valve means mounted in different ones of said branches to direct at least the greater portion of said fluid ow in one direction through one of said branches and in the opposite direction through the other of said branches, the operation of said check valve means providing an indication of the direction of said iiuid flow, detector means responsive to said relative velocity and adapted to be positioned in said fluid medium, said detector means being connected to said fluid connections to cause fluid ow in said branches between said connections in opposite directions to activate said indicator means when said relative velocity increases and decreases respectively, and

a uid pressure balancing device comprising a pressure tight housing, a diaphragm connected across and dividing said housing into a pair of fluid pressure chambers, at least a first of said chambers having a cross-sectional area which progressively decreases away from said diaphragm, said diaphragm being highly resilient so that progressive increase in the pressure of the second chamber relative to said iirst chamber causes said diaphragm to iiex into increasing engagement with the inner wall of said first chamber to decrease progressively the effective area of said diaphragm extending across said housing, said balancing device being connected between one of said fluid connections and said detector means with one of said chambers in uid communication with said one fluid connection and the other of said chambers being in fluid communication with said detector means to stop the uid ow in said loop when said relative velocity becomes constant.

24. An apparatus for indicating pressure change which comprises conduit means, resiliently yieldable Wall means extending across said conduit means to provide a iluid seal, said conduit means being connectable on opposite sides of said wall means respectively to first and second sources of fluid under iirst and second pressures variable from each other thereby exposing the opposite side of said wall means to diierential pressure so that said wall means yields and uid ows in said conduit means in response to variation in said differential and said wall means comes to rest and uid ceases to flow in said conduit means when said differential becomes constant, indicator means including a moveable element positioned in said conduit means between said sources and responsive to fluid ilow to indicate a change in said differential, and means to maintain said element at a predetermined location along said conduit means in the absence of fluid liow to indicate constant diierental regardless of the position of said wall means.

25. An apparatus as recited in claim 24 wherein the cross sectional area of said conduit means is substantially less at the location of said element than at the location of said wall means.

References Cited in the tile of this patent UNITED STATES PATENTS 1,023,132 Custer Apr. 16, 1912 1,352,391 Starling et al Sept. 7, 1920 1,451,064 Dunajet Apr. 10, 1923 2,008,885 Upson July 23, 1935 2,009,427 Bentzel July 30, 1935 2,679,760 Hartland et al June 1, 1954 2,715,705 Barstow et al Aug. 16, 1955 2,776,829 Cockram Ian. 8, 1957 2,825,361 Seljos Mar. 4, 1958 FOREIGN PATENTS 200,530 Great Britain Oct. 10, 1924 545,527 Italy July 3, 1956 

1. AN APPARATUS FOR INDICATING CHANGE IN THE RELATIVE VELOCITY BETWEEN SAID APPARATUS AND A FLUID MEDIUM WHICH COMPRISES CONDUIT MEANS, RESILIENTLY YIELDABLE WALL MEANS EXTENDING ACROSS SAID CONDUIT MEANS TO PROVIDE A FLUID SEAL, SAID CONDUIT MEANS BEING CONNECTABLE ON ONE SIDE OF SAID WALL MEANS TO A SOURCE OF FLUID UNDER A FIRST PRESSURE, MEANS RESPONSIVE TO SAID RELATIVE VELOCITY AND CONNECTED TO SAID CONDUIT MEANS ON THE OTHER SIDE OF SAID WALL MEANS TO EXPOSE SAID OTHER SIDE TO A SECOND FLUID PRESSURE VAYING FROM SAID FIRST PRESSURE IN PROPORTION TO SAID RELATIVE VELOCITY THEREBY CAUSING SAID WALL MEANS TO RESILIENTLY YIELD AND FLUID TO FLOW IN SAID CONDUIT WHEN SAID RELATIVE VELOCITY CHANGES AND SAID WALL MEANS TO COME TO REST AND THE FLUID FLOW IN SAID CONDUIT TO CEASE WHEN SAID RELATIVE VELOCITY BECOMES CONSTANT, INDICATOR 